Actuators, such as those used in heating, ventilation and air conditioning (HVAC) systems, typically comprise a direct current (DC) motor, an output gear driven by the motor, a potentiometer for monitoring the position of the gear, and a socket having five terminals, two motor terminals for the motor and three terminals for the potentiometer. The potentiometer has a resistive track having first and second ends and a wiper which is arranged to make sliding contact with the resistive track to provide a signal indicative of the rotational position of the output gear. The first and second ends are connected to first and second terminals of the socket and the wiper is connected to a third terminal of the socket known as the position terminal. The motor is provided with a first DC power source, such as 12 volts, via the two motor terminals of the socket. The two terminals connected to the resistive track of the potentiometer are connected to a second DC power source, such as 5 volts. The position terminal thus provides a feed back signal corresponding to the position of the output gear. The polarity of the two motor terminals has to be switched to change the rotational direction of the motor. This means we can not eliminate a terminal of the socket by directly connecting the ground terminal of the potentiometer to the ground terminal of the motor, as the motor has no consistent ground terminal.
The present invention aims to provide a new actuator which can solve or at least mitigate the above mentioned problem.